I read the first edition of this book years ago and, wanting to get back into Rails, I read it again to bring myself back up to date.
It was good to read the major differences since Rails 0.9, although most of the book was not new to me. Most importantly, however, it's given me all the right pointers in the direction of where to go next to learn the specifics I need for my projects.
This was the first book I read when learning Ruby on Rails. I highly recommend it as the text is easy to follow, concepts are presented well, and the examples are fun and interesting. I still keep it by my computer when I work on projects to use as a reference guide.